Winding apparatus with programmed torque control

ABSTRACT

This disclosure relates to a programmed torque control system for winding a web of material supplied at constant tension, into a roll of material having predetermined tensive gradations throughout, by controlling the magnitudes of the torques developed by a pair of drum winders, in accordance with a selected program.

United States Patent Curtis L. Ivey Williamsville, N.Y.

July 13,1970

Oct. 5, 1971 Westinghouse Electric Corporation Pittsburgh, Pa.

Inventor Appl. No. Filed Patented Assignee WINDING APPARATUS WITH PROGRAMMED TORQUE CONTROL 8 Claims, 8 Drawing Figs.

U.S. Cl 3l8/7, 3 l 8/45 Int. Cl H02p 5/46, B65 h 59/00 Field oi'Search 318/6, 7, 45, 46

[56] References Cited UNITED STATES PATENTS 3,156,397 11/1964 Davies 318/6 3,372,320 3/1968 Boyum 318/6 Primary Examiner-Cris L. Rader Assistant Examiner-Thomas Langer Attorneys-F. H. Henson, R. G. Brodahl and J. J. Wood ABSTRACT: This disclosure relates to a programmed torque control system for winding a web of material supplied at constant tension, into a roll of material having predetermined tensive gradations throughout, by controlling the magnitudes of the torques developed by a pair of drum winders, in accordance with a selected program.

WINDING APPARATUS WITH PROGRAMMED TORQUE CONTROL BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to a programmed torque control system for two drum winders for winding a web of material into a roll having predetermined tensive gradations throughout. 7

2. Description of the Prior Art Various manufactures of raw materials such as paper, textiles, plastics and the like, find it advantageous to ship the raw material to the consumer in the fonn of a shipping roll wound on a core. Empirical evidence suggests that a roll with better handling capabilities may be provided if a web of the raw material is wound with variable tensive force, in accordance with programmed graduations, which depend upon the nature of the material as well as the manufactures know-how. For example, some manufactures feel that the greatest tensive force should be applied to the material at the beginning of the roll, the material being tightly wound on a core, with gradual lessening of the tensive force as the roll increases in diameter.

In one typical arrangement, winding is accomplished with a configuration of two rotating drums in which a web of material is adapted to pass up between the two drums located in spaced relationship to each other, and then pass around a small core, the tension on the material being rolled being then progressively decreased or increased in accordance with some program detennined by the manufacturer.

One method in use in prior art is to couple both drums to their respective prime movers through variable speed mechanical drives. The speed ratio of the drums is then varied slightly to develop different torques, the speed differential being programmed in accordance with the increasing diameter of the wound roll. While this technique works fairly well, it is limited to narrow ranges, and the increase in required mechanical components, concomitantly increases maintenance costs.

Another common technique is to drive each drum with a DC motor; the back drum motor (by definition the motor nearer to the entering web of material) is speed or voltage regulated, while the front motor is current regulated to thereby torque regulate the front drum. This technique has several disadvantages. One is that when the winder is being threaded, there is no force to hold the drum speeds in synchronism, and a current regulated drum will accelerate to saturation or even destruction, if its speed is not limited by some dead-band arrangement. The dead-band is necessary because in order to operate normally, the voltages of the two motors are of necessity different because of difi'erences in IR drop resulting from different torques. A typical overspeed may be 2400 percent. This is obviously quite unsafe. Another disadvantage is that with a fixed or programmed current for the front drum motor, unless some method of inertial compensation is provided, the back drum will provide all the inertial torque, thus upsetting any desired torque division between drums. While it is perfectly true that these factors may be taken into account and satisfactory compensation made, nevertheless, performance is expensively satiated in terms of added hardware: operational amplifiers, tachometers, logic circuitry and so forth, thus contributing not only to higher initial costs, but also to continuing maintenance expense.

Still another method is to regulate or control the field of the front drum motor. This is perhaps the most crude technique, suffering from nonlinearity and unsuitability at low speeds and low tensions.

SUMMARY OF THE INVENTION This invention relates to a programmed torque control system for winding a web of material, supplied at constant tension, into a roll of material having programmed tensive gradations throughout, by controlling the magnitudes of the torques developed by first and second drum winders, driven by electric motors respectively. Means are provided for speed regulating the motor for the second drum. Means are also provided for obtaining control signals which are a function of the torque magnitudes selected for the respective drum winders. Finally, means are provided for voltage regulating the motor associated with the first drum, which latter means are connected to the terminals of the first motor, and coupled both to the varying control signal means and to the terminals of the second motor, the terminal voltage of the first motor being then a function of the varying control signals and the tenninal voltage of the second motor.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic diagram showing two drum winders coupled to respective electric motor drives, and showing a web of material being fed from a supply reel for winding on a core;

FIG. 2 is an electrical schematic depicting the torque program control circuitry in accordance with the invention;

FIGS. 3A, 3B, 3C, and 3D are diagrams used in explaining the torque program distribution between the front and back drums;

FIG. 4 is a schematic diagram showing the voltage and speed regulation arrangement for the front and back drum motors respectively, in accordance with one illustrative embodiment of the invention; and

FIG. 5 is an electrical schematic showing the voltage and speed regulation arrangement for the front and back drum motors respectively, in accordance with another illustrative embodiment of the invention.

DESCRIPTION OF THE EXEMPLARY EMBODIMENTS Referring now to FIG. 1, there is shown a typical two-drum winder arrangement. A spool of material 10, processed by the manufacturer, unwinds a web of material 12 which is under constant tension provided in any convenient manner such as by means of tensive regulator 14, to the drum winders identified at l6, 18. The drums l6 and 18 are driven by DC shunt motors indicated symbolically at 20 and 22 respectively. The drum 16 is further identified as the second or back drum, and the drum 28 is further identified as the first or front drum. By convention in the industry, the drum farthest from the entering web material is denominated the front drum. As indicated by the directional arrows, both drums are driven counterclockwise. The web of material 12 passes under drum l6 and then around a core 24, the roll of material gradually building up to the finished roll 26. A roller or rider 28 transmits some force (supplied pneumatically or hydraulically) to hold the emerging roll tightly against the surface of the two drums. The core 24 is forced down against the drums mechanically to prevent slippage, the force being gradually reduced as the weight of the growing roll increases to substitute in whole or in part for this force. The object of winding is to produce a high quality shipping roll, and to that end it is usually desirable that the initial tension applied in rolling, gradually tapers off so that the inner wraps are wound much tighter on the core 24 than are the outer wraps. Most manufacturers of raw materials have their own winding schedule to satisfy their own requirements. The instant invention is not intended to adopt any particular winding program, but instead discloses a control system which will provide any programmed torque which may be desired in accordance with the specifications of the manufacturer based on his own specific requirements.

The invention proposes that the terminal voltage of the front drum motor be voltage requlated, in accordance with a torque program distribution between both drums, to enable more precise control than the current regulation schemes of the prior art, while at the same time eliminating the difficulties with the present prior art systems. The front and back drum motors may be connected in accordance with the arrange ments shown in either FIG. 4 or FIG. 5.

The mathematics involved in providing the voltage increment to secure voltage regulation is derived as follows:

V= terminal voltage of the motor E counter EMF of the motor I= the armature current R the armature resistance (for simplicity assume motors have the same ratings). and the subscripts F and B designate the voltage and current parameters associated with the front and back drum motors respectively.

As will be made clear as this description proceeds, it is intended that the back drum motor, be speed regulated and the front drum motor be voltage regulated. Accordingly, an increment or decrement voltage V x will be added to the magnitude of the voltage for the back drum motor V,, in accordance with the following formula:

r= xn The relationship which V bears in the arrangements of FIG. 4 and 5 will be described later. When the web of material is initially threaded, the tension is zero and therefore V X is zero.

(5) or E,-+I,.;R=E +I R Since there is no tension and the IR drops will provide the only losses, the no load voltage IR drops are equal, and E,=E,,. Since the counter EMF of each motor is equal and they have equal fluxes, their speeds are equal and there is no overspeed of either drum.

Under the nonnal running conditions, the drum motors are mechanically coupled and thus their speeds and counter EMFs are equal or (l0) l-,-=l,-+l,, where I, is the total of the currents and comprises:

a. the total tension torque b. inertial torque c. loss torque Solving equations (9) and 10) for I,- and I If 1 changes as a result of an increase in losses or in speed changes (inertial torque) then:

Since both increase in the same order of magnitude, the tension component remains the same, and the two drives compensate for their own inertial and other losses.

It can be demonstrated that in an adjustable speed drive by voltage control that (20) r= where Tis total web tension.

The torque program circuitry of FIG. 2 provides a corrective voltage e in accordance with the following:

e, corrective voltage a an operator's adjustment (potentiometer) in the region (0l) which determines the magnitude of the torque developed by the front drum 18, at the completion of the winding operation.

I: an operators adjustment (potentiometer) in the region (0-l which determines the magnitude of the torque developed by the front drum at the beginning of the winding operation.

D= a multiplier decreasing monotonically from l to 0) as a function of the increasing roll diameter.

e, a voltage proportional to the constant tension l =kT This equation was empirically determined to afford total tensive distribution between the two drum motors so that the motors can assume any predetermined portion of the total tensive load between zero and 100 percent, respectively. The torque program control circuitry for realizing equation (2l is shown in FIG. 2. The circuitry comprises operational amplifiers indicated at 30, 32, 34 and 36 having respective gains indicated on the drawing. The output of the operational amplifier 30 is connected to potentiometers 38 and 40 as indicated. As may be seen from FIG. 2, the potentiometer 38 supplies the a adjustment and potentiometer 40 supplies the b" adjustment. The slides 42 of potentiometer 38 is connected as one input to operational amplifiers 34 and 36 respectively. The slide 44 for the potentiometer 40 supplies the input to the operational amplifier 32. The output of operational amplifier 32 is connected as an input to operational amplifier 34. The output of the operational amplifier 34 is connected across a potentiometer 46, the slide 48 being connected as one input to theoperational amplifier 36. The slide 48 of the potentiometer 46 is coupled by a cam arrangement, indicated symbolically at 50, so that it is driven as a function of the enlarging diameter of the roll FIG. 1: 26. A calibrating potentiometer 52 is connected between the output of amplifier 36 and ground, and by means of slide 54 the magnitude of V may be adjusted.

OPERATION OF THE CIRCUITRY OF FIGURE 2 The input to the circuitry e, is a function of the total tension T. Following through the branch parts of the circuitry:

The output e, then may be adjusted by means of the calibration potentiometer 52 to provide the actual signal correction voltage V As may be seen from a study of equation (27) when D=0 all the contribution to output e, is made by the a" potentiometer 38. The (2" potentiometer 38 effects only the end of the program, and the b" potentiometer effects only the start of the program. At the beginning of the winding program D=l. Therefore from a study of equation (27) the voltage e, is a function of (2bl At the end of the program D=0 and therefore the corrective voltage is a function of 2al A few of the possible torque control programs are indicated in FIGS. 3A, 3B, 3C and 3D, which depict the per unit web tension versus the per unit diameter for various "0 and b" adjustments selected by the operator. The figures show typical curves for various values of a and b" as the programmed diameter varies from the core to the end of the program diameter, which in each of the cases has arbitrarily been selected as one-half the maximum roll diameter. The solid line in each of these figures indicates the tension of the front drum and the dashed line identifies the tension of the back drum.

Considering for a moment FIG. 3A, it will be seen that when a is equal to 0.5 and b=l at the beginning of the program the front drum supplies all the tension while the back drum supplies zero. The tension on the front drum is gradually decreased as indicated, and finally stabilizes at a point where each drum is supplying one-half the total tension. In the program depicted in FIG. 3C the back drum (as indicated by the dashed line) at the end of the program supplies 70 percent of the total tension and the front drum supplies 30 percent. In FIG. 3B the front drum supplies 70 percent of the total tension and the back drum supplies 30 percent. In FIG. 3D the back drum supplies percent and the front drum supplies 20 per cent.

FIGURES 4 AND 5 EMBODIMENTS The corrective voltage V may be utilized with either the system shown in FIG. 4 or that shown in FIG. 5. In FIG. 4 the motor 20 is energized by a generator 56. The motor 22 for the front drum 18 is connected in series with a booster generator 58, the serial combination of motor 22generator 58 being connected in parallel with the generator 56. The back drum motor is speed regulated, a tachometer 60 supplying an error voltage to the summation junction 62. A speed reference voltage is also applied to the summation point 62 and any dif- 5 ference is amplified by the amplifier 64 and applied to the field 66 of the generator 56.

The motor 22 is voltage regulated by the torque program control circuitry of FIG. 2. The corrective voltage V is supplied to the summation junction 68. A voltage from the booster generator 58 is fed back at 70 to the summation point 68 and any difference is amplified by the amplifier 72 and applied to the field 74 of the generator 58. Thus the terminal voltage of the motor 22 is that of the generator 56 plus whatever increment is supplied by the booster generator 58.

In the arrangement of FIG. 5 separate generators are provided for each motor. The motor 20 is connected to generator 76 as indicated. The motor 20 is speed regulated by means of tachometer 78 which supplies an error voltage to the summation junction 80. A speed reference is also applied to the summation junction 80 and any difference is amplified by the amplifier 82 and applied to the field 84 of the generator 76. The motor 22 is supplied by a generator 86. The corrective voltage V is fed to the summation junction 88, and there is also fed to this junction a feedback voltage from the back drum motor at 90. The voltage of the generator 86 is also fed back at 92 to the summation junction 88. Typically V is the back drum voltage at 90 is also and the feedback 92 is negative; any difference is then fed to the amplifier 94 and applied to the field 96 of the generator 86. The terminal voltage of the motor 22 is then a function of V as well as the voltage of the back drum motor 20. It should be noted at this point that the voltage supply need not be obtained from rotating equipment, but static supplies, thyristors or the like may also be used.

It will therefore be apparent there has been disclosed a torque program control system having wide applicability for industrial users, where the torque produced by separate drums respectively, is to be controlled in accordance with a preselected program for torque distribution between dual winding drums.

I claim as my invention:

1. A programmed torque control system for winding a web of material supplied at constant tension, into a roll of material having programmed tensive gradations throughout, by controlling the magnitudes of the torques provided by first and second drum winders driven by first and second electric motors respectively, comprising:

a. means for speed regulating said second motor;

b. means for providing varying control signals which are a function of the torque magnitude selected for the respective drum winders;

c. means for voltage regulating said first motor, connected to the terminals of said first motor, and coupled both to said varying control signal means and to the terminals of said second motor, the terminal voltage of said first motor being a function of both said varying control signals and the terminal voltage of said second motor.

2. A programmed torque control system according to claim 1 wherein:

said voltage regulating means comprises variable voltage supply means in series with said first motor, the serial combination being electrically in parallel with said second motor, said varying control signals being applied to said voltage supply means to vary the output thereof. 3. A programmed torque control system according to claim 1 wherein:

said voltage regulating means comprises variable voltage supply means and voltage summation means, said variable voltage means being connected across the terminals of said first motor and having a feedback path connected to said voltage summation means, said voltage summation means being coupled to said second motor and to said varying control signal means and having a summation output connected to said variable voltage supply means to vary the voltage output thereof.

4. A programmed torque control system for winding a web of material supplied at constant tension into a roll of material having programmed tensive gradations throughout, by controlling the magnitudes of the torques provided by first and second drum winders driven by first and second electric motors respectively, comprising:

a. means for speed regulating said second motor;

b. means for providing varying control signals which are a function of:

where a an operator adjustment in the region (0 to l) which determines the magnitude of the torque developed by the first drum at the completion of said roll;

b an operator adjustment in the region (Oto l) which determines the magnitude of the torque developed by the first drum at the beginning of the rolling operation.

D= a multiplier decreasing monotonically from I to 0 as a function of the increasing roll diameter.

e a voltage proportional to said constant tension and c. means for voltage regulating said first motor, connected to the terminals of said first motor and coupled to said varying control signal means and to the terminals of said second motor, the terminal voltage of said first motor being a function of both said varying control signals and the tenninal voltage of said second motor.

5. A programmed torque control system according to claim 2 wherein said variable voltage supply means is an electric generator.

6. A programmed torque control system according to claim 3 wherein said variable voltage supply means is an electric generator.

7. A programmed torque control system according to claim 2 wherein said variable voltage supply means is an electric generator having a field winding to which said variable control signals are applied.

8. A programmed torque control system according to claim 3 wherein said variable voltage supply means is an electric generator having a field winding to which said summation output is applied. 

1. A programmed torque control system for winding a web of material supplied at constant tension, into a roll of material having programmed tensive gradations throughout, by controlling the magnitudes of the torques provided by first and second drum winders driven by first and second electric motors respectively, comprising: a. means for speed regulating said second motor; b. means for providing varying control signals which are a function of the torque magnitude selected for the respective drum winders; c. means for voltage regulating said first motor, connected to the terminals of said first motor, and coupled both to said varying control signal means and to the terminals of said second motor, the terminal voltage of said first motor being a function of both said varying control signals and the terminal voltage of said second motor.
 2. A programmed torque control system according to claim 1 wherein: said voltage regulating means comprises variable voltage supply means in series with said first motor, the serial combination being electrically in parallel with said second motor, said varying control signals being applied to said voltage supply means to vary the output thereof.
 3. A programmed torque control system according to claim 1 wherein: said voltage regulating means comprises variable voltage supply means and voltage summation means, said variable voltage means being connected across the terminals of said first motor and having a feedback path connected to said voltage summation means, said voltage summation means being coupled to said second motor and to said varying control signal means, and having a summation output connected to said variable voltage supply means to vary the voltage output thereof.
 4. A programmed torque control system for winding a web of material supplied at constant tension into a roll of material having programmed tensive gradations throughout, by controlling the magnitudes of the torques provided by first and second drum winders driven by first and second electric motors respectively, comprising: a. means for speed regulating said second motor; b. means for providing varying control signals which are a function of: ((2a-1)+2(b-a)D)ein where a an operator adjustment in the region (0 to 1) which determines the magnitude of the torque developed by the first drum at the completion of said roll; b an operator adjustment in the region (0to 1) which determines the magnitude of the torque developed by the first drum at the beginning of the rolling operation. D a multiplier decreasing monotonically from 1 to 0 as a function of the increasing roll diameter. ein a voltage proportional to said constant tension and c. means for voltage regulating said first motor, connected to the terminals of said first motor and coupled to said varying control signal means and to the terminals of said second motor, the terminal voltage of said first motor being a function of both said varying control signals and the terminal voltage of said second motor.
 5. A programmed torque control system according to claim 2 wherein said variable voltage supply means is an electric generator.
 6. A programmed torque control system according to claim 3 wherein said variable voltage supply means is an electric generator.
 7. A programmed torque control system according to claim 2 wherein said variable voltage supply means is an electric generator having a fiEld winding to which said variable control signals are applied.
 8. A programmed torque control system according to claim 3 wherein said variable voltage supply means is an electric generator having a field winding to which said summation output is applied. 